The driver of a vehicle should be aware of the speed limit of the road upon which they are driving. Unfortunately, currently the only way for a driver to know the speed limit of a road is to observe posted speed limit signs, or to know the rules of a given city, area or type of road as to the speed limit when no signs are posted. Posted speed limit signs are problematic because such signs may only be located infrequently on any given stretch of road. As such, a driver turning onto the road may not be notified of the speed limit in a timely manner. Another disadvantage of such posted speed limit signs is that they are often obstructed from view by trees, shrubs and other signs. Further, even if not obstructed, such speed limit signs may be difficult to see among the myriad of signs and advertisements typically found in urban and suburban areas. Additionally, if a driver is new to a particular stretch of road, or is trying to find a location on the road, such posted speed limit signs may be outside of the driver's focus of attention and may be easily missed. Thus, posted speed limit signs often provide less than adequate notice of the speed limit for that road to a driver of a vehicle.
Alternately, many drivers are not familiar with local speed limit rules, such as on city streets where speed limit signs are often not posted. For example, these areas rely on postings located at the perimeter of the area, such as a sign reading “city speed limit of 25 mph unless otherwise posted,” and if the driver does not notice these signs prior to entering the area, they may never again be notified of the speed limit within the area. Thus, many drivers lack knowledge of the rules of a given city, area or type of road as to the speed limit.
There are systems, such as cruise control systems, that help a driver to maintain a vehicle at a desired speed limit value set by the driver. The disadvantage of these systems, however, is that the desired speed limit value will not change until manually altered or cancelled. These cruise control systems do not include any mechanism to notify the driver of a speed limit of a road, or to automatically adjust the desired speed limit value based upon a change in the speed limit of the road.
Therefore, improved apparatus and methods are desired to aid a driver in managing and controlling the speed of a vehicle in relation to a speed limit for the road or transit route upon which they are traveling.